JP2009262521A - Transfer foil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transfer foil can obtain a variety of sharp embossed patterns by using the same die in an in-mold transfer molding. <P>SOLUTION: On one surface of a flexible film, a mold release layer, a protective layer, a pattern layer, and a bonding layer are formed, and on the opposite surface, an embossed pattern layer is installed for this transfer foil. In the transfer foil, the protective layer is constituted of an ultraviolet ray or electron beam curing type resin. Before the resin is molded, the curing degree is adjusted to have a glass transition temperature of 30 to 150°C, and the transfer foil is re-cured after the resin is molded. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a transfer foil that can express unevenness of various patterns in a transfer foil used in in-mold molding of a resin.

  Resin-molded products are widely used for parts such as home appliances, mobile phones, and automobiles because they are easy to mold, lightweight, and can be decorated in various ways. Conventionally, the surface treatment of resin molded products has been performed by painting, but the workability is poor and it is not suitable for beautiful decoration. Furthermore, the working environment was poor due to the use of organic solvents.

  As an improvement, a release layer is provided on the plastic film, and a protective layer, a picture layer, and an adhesive layer are provided on the plastic film. The mold is inserted into a mold for resin molding, and the resin is inserted into the adhesive layer side for molding. The molding method in which the film is peeled off and the portion below the protective layer is transferred to a resin molded product has been widely used. Thus, surface processing can be performed simultaneously with resin molding, workability is improved, and various high-design inks such as metallic gloss ink and pearl ink can be used, and high-design processing is possible. Furthermore, there is an advantage that the working environment is improved because the use of the organic solvent is eliminated, and the use is increasing in recent years.

  In particular, a resin layer is separately provided on the opposite surface of the transfer foil, and an uneven expression having various variations is obtained by using a single mold depending on the pattern. For example, in JP-A-01-114499, a film is provided with a protective layer, a picture layer, an adhesive layer and a resin layer that forms an uneven layer on the opposite surface, and various uneven expressions can be easily expressed with the same mold. Is disclosed. A case is disclosed in which PET, PP, nylon, etc. are used as the film, a thermoplastic resin such as vinyl resin, cyclized rubber chlorinated rubber resin, acrylic resin, or ultraviolet ray or electron beam curable resin is used as the protective layer. Yes. By using this method, it is possible to express various variations of unevenness with the same mold, which is advantageous for small lot production.

  The protective layer in this case is desired not to be deformed at a high temperature during resin molding, to be hard to be damaged during use, and to remain unchanged even when oil, organic solvent, detergent, etc. are applied. Therefore, ordinary thermoplastic resins are easily deformed at high temperatures, have low hardness and are easily damaged, and it is difficult to obtain protective layers having various resistances. On the other hand, when UV or electron beam curable resin is used, it is difficult to be deformed at high temperatures, scratches are difficult, and various protective layers can be obtained. However, the resin is too hard to follow unevenness during molding. In other words, cracks may occur, adhesion with the molding resin may decrease, or fine unevenness may not be expressed.

Problems to be solved by the invention

  As described above, when an uneven pattern layer is provided on the opposite side of the transfer foil and an ultraviolet ray or electron beam curable resin is used for the protective layer, resin molded products having excellent heat resistance, surface hardness, and various resistances can be obtained. There was a problem in obtaining fine irregularities. An object of the present invention is to provide a transfer foil that can obtain a fine concavo-convex expression using an ultraviolet ray or an electron beam curable resin as a protective layer.

  Therefore, the present inventors have earnestly studied and obtained the idea that the degree of curing of the ionizing curable resin is controlled, can easily follow irregularities at the time of molding, and can further increase the degree of curing after molding. Was completed.

Means for solving the problem

  In the transfer foil according to claim 1 of the present invention, a release layer, a protective layer, a pattern layer, and an adhesive layer are provided on one side of a flexible film, and an uneven pattern resin layer is formed on the opposite side. In a transfer foil that is mounted on a molding die, filled with resin in the die, and in-mold molding is performed, the protective layer is formed of ultraviolet light or electron beam curable resin, and the degree of curing is adjusted to change the glass transition of the resin. It is characterized by comprising a protective layer having a temperature of 30 to 150 ° C.

  The transfer foil according to claim 2 of the present invention is the transfer foil according to claim 1, wherein the ultraviolet ray and the electron beam curable resin are made of an acrylic resin, a styrene acrylic resin, a styrene resin, or an epoxy acrylic resin. It is a feature.

  Embodiments of the present invention will be described below.

  FIG. 1 shows an embodiment of the present invention, wherein 1 is a flexible film, 2 is a release layer, 3 is a protective layer, 4 is a pattern layer, 5 is an adhesive layer, and 6 is the opposite of the film. It is the uneven | corrugated pattern layer provided in the side.

  As the flexible film, various materials such as polyethylene, polypropylene, polyethylene terephthalate, nylon, vinyl chloride, and vinylidene chloride are used. It is better to select the resin considering the heat resistance depending on the molding resin. The thickness is preferably 15 to 70 μm.

  For the release layer, melamine resin, acrylic resin, silicon resin, wax or the like is used. Various coatings such as a gravure coater, a roll coater, a screen coater, a flexo coater, and a reverse coater are used for coating. The coating thickness is 0.5-5 μm.

  For the protective layer, an ultraviolet curable resin or an electron beam curable resin is used. It has a prepolymer having an unsaturated bond in the molecule, an oligomer, and a monomer. When using an ultraviolet curable resin, a photopolymerization initiator is preferably added. Examples of the resin include an acrylic resin, a styrene acrylic resin, a styrene resin, and an epoxy acrylic resin.

  The degree of curing is preferably adjusted by adjusting the intensity of ultraviolet rays or electron beams so that the glass transition temperature is 30 to 150 ° C. If the temperature is low, the resin heats up during molding and may be pulled by the movement of the resin (so-called gate jump occurs). Moreover, even if recured, excellent resistance may not be obtained. If it is too high, the resin becomes hard and cracks and poor adhesion to the resin body occur during molding.

  The thickness of the protective layer is preferably from 0.5 to 15 μm, and more preferably from 5 to 15 μm in order to obtain particularly strong resistance. If it is thin, it will be difficult to obtain strength, and if it is thick, it will be difficult to follow unevenness, and it will not be possible to obtain beautiful unevenness expression.

  For the pattern layer, various printing methods such as a gravure printing machine, an offset printing machine, a screen printing machine, a letterpress printing machine, and a flexographic printing machine are used. In order to maintain the heat resistance of the ink, an ultraviolet curable resin or a two-component curable resin is preferable.

  The adhesive layer is preferably selected in consideration of compatibility with the molding resin. A vinyl chloride resin, an ethylene vinyl acetate resin, an acrylic resin, a vinyl acetate vinyl resin, or the like is used. The thickness is preferably 1 to 3 μm. When the molding temperature is higher than the heat resistance temperature of the adhesive layer resin, a two-component curable heat-resistant layer may be provided in order to prevent ink flow (so-called gate jump) of the pattern layer during molding.

  Various printing systems such as a gravure printing machine, a screen printing machine, an offset printing machine, a letterpress printing machine, and a flexographic printing machine can be used for the concavo-convex pattern resin layer. In consideration of heat resistance, the ink is preferably ionizing radiation ink or two-component curable ink. Various thicknesses of 1 to 30 μm can be provided. Screen printing is particularly suitable for increasing the thickness.

  Using the transfer foil produced as described above, it is inserted into a resin shaping mold and resin molding is performed. FIG. 2 shows the molding procedure. 7 is a resin molding die, and 8 is a portion into which resin is inserted (generally called a gate). Reference numeral 9 denotes a transfer foil, in which the concavo-convex pattern printed layer is set so as to be opposite to the gate into which the resin is inserted, and the adhesive layer side is in contact with the molded resin layer. The heat-melted resin is inserted into the mold at a predetermined pressure, and after cooling, the molded resin is taken out from the mold, the film is peeled off from the release layer, and the pattern is transferred to the resin layer. At that time, the portion having the concavo-convex pattern layer becomes a concave portion.

  Thereafter, in order to sufficiently cure the protective layer, the final resin molded product is obtained by reirradiating with ultraviolet rays or electron beams.

  Next, an Example demonstrates this invention.

  As the flexible film, a commercially available PET film was used. Thicknesses of 25 μm, 38 μm, and 50 μm were used.

  A silicone release agent was applied to the flexible film with a gravure coater. After drying, it was baked with hot air at 180 ° C. The coating thickness is 0.5 μm.

  A protective layer is applied to the release-treated film. As the resin for the protective layer, an acrylic ultraviolet curable resin was used. The coating thickness is 2 μm and 10 μm.

  In order to clarify the relationship between the degree of curing, the unevenness expression, and the surface properties, the illuminance of the UV lamp was changed and the test was performed. The irradiation energy was measured with an integrating light meter. As a comparative example, samples were also prepared in the case where ultraviolet irradiation was not performed and in the case of complete curing. In order to confirm the degree of curing, the glass transition temperature was measured.

The produced transfer foil is as shown in Table 1 below.

  A pattern layer is printed on the protective layer. Printing was performed with a gravure printing machine. As the ink, a commercially available water-based acrylic ink was used. Moreover, the adhesive layer was also performed with the gravure printing machine. The adhesive used is a water-based acrylic resin.

  On the opposite surface of the transfer foil, an uneven pattern layer was printed with a screen printer. A two-component curable vinyl urethane ink was used. In order to give an idea of printing the picture layer, an ink added with a titanium oxide pigment was used.

  The following transfer foil was molded using a resin molding machine. The resin used is PMMA. The film was peeled off from the molded resin, transferred, and then re-cured by irradiation with ultraviolet rays. The irradiation energy is 500 mj.

About the performance of the molded final molded product, pencil hardness, alcohol resistance, and solvent resistance were confirmed and evaluated. Each measurement method is as follows.
Pencil hardness: A compliant test according to JIS K5600.
Alcohol resistance: A cloth was dipped in ethanol and wiped 20 times to see the change.
Solvent resistance: MEK was impregnated into a cloth and wiped 20 times to observe changes.

The performance of the molded product is as follows.

The invention's effect

  As described above, the protective layer is made of an ionizing radiation curable resin such as an ultraviolet curable resin, and the glass transition temperature of the resin is controlled to be within a range of 30 ° C. to 150 ° C. It provides a clear representation of unevenness and does not crack during molding. Moreover, the surface physical property excellent in tolerance is obtained.

Industrial applicability

  The present invention, which can obtain various variations of irregularities simply by changing the type of transfer foil with the same mold, eliminates the need to create a new mold and to change the mold. It is suitable for small-lot production and has a great potential for industrial use.

An example of the transfer foil of this invention is shown, and is sectional drawing. It is a sectional view showing the resin molding process of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Flexible film 2 Release layer 3 Protective layer 4 Picture layer 5 Adhesive layer 6 Concavity and convexity pattern layer 7 Resin molding die 8 Resin insertion slot (gate)
9 Transfer foil

Claims (2)

A release layer, a protective layer, a pattern layer, and an adhesive layer are provided on one side of the flexible film, and an uneven pattern resin layer is formed on the opposite side, and then mounted on a resin mold, and the resin is applied to the mold. In a transfer foil that is filled and in-mold molded, the protective layer is formed of an ultraviolet ray or electron beam curable resin, and the glass transition temperature of the resin is 30 to 150 ° C. by adjusting the degree of curing. Transfer foil characterized by 2. The transfer foil according to claim 1, wherein the ultraviolet ray and electron beam curable resin comprises an acrylic resin, a styrene acrylic resin, a styrene resin, or an epoxy acrylic resin.

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